Top Ten iPhoto Tips
Subject:   Tip 9 - necessary? - No, you gain nothing and waste disk space, slow down iPhoto
Date:   2002-07-26 01:04:43
From:   laird
Response to: Tip 9 - necessary? - No, but a good idea.

You don't need to make duplicates before editing, because (as others pointed out) iPhoto already does this for you. If you want to go back to the original without losing your edited version, it makes more sense to duplicate the edited image, then restore the original.

If you duplicate all photos that you clean up, you end up with at least one extra copy of the photo, and at 1 MB per image, that adds up. Also, you end up with a really cluttered iPhoto library, making it harder to keep track of things, and slowing the app down.